msm8974: Audio tunings

 * Enable some things for future use
 * Tweak volume stepping/ramping

Change-Id: I6f830dda1f57e8edece61df88a38c048c96a2524
msm8974: Improve thermal mitigation

Change-Id: I3c576bf937cdf1252d0d882d4741d096201ba2ec
msm8974: Use the normal speaker output

 * These speakers are differential, not stereo.

Change-Id: I678bdc99314768fcc02a1db5f32c8809bd2d15a1